Bertrand



March 17, 1964 a. BERTRAND 3,125,050

CONTROL SYSTEM FOR ELECTRIC SEWING MACHINES Filed March 6, 1961 5 Sheets-Sheet l IIVMEIVTOR GEO/765$ 6537x000 I m Ju J JW Ar-romvs) March 17, 1964 G. BERTRAND CONTROL SYSTEM FOR ELECTRIC SEWING MACHINES Filed March 6, 1961 FIG. 2

5 Sheets-Sheet 2 Arman/E March 17, 1964 G. BERTRAND ,1

CONTROL SYSTEM FOR ELECTRIC SEWING MACHINES Filed March 6, 1961 5 Sheets-Sheet 3 6505055 Barr-Mun Arr-0mm) March 17, 1964 G. BERTRAND 3, 5,0

CONTROL SYSTEM FOR ELECTRIC SEWING MACHINES Filed March 6, 1961 5 Sheets-Sheet 4 F/ OTS I A/VE/v'roR Gzoxess BERTRA IVD I A'rrok IVE! March 17, 1964 a. BERTRAND 3,125,050

CONTROL SYSTEM FOR ELECTRIC SEWING MACHINES Filed March a, 1961 5 S heets-Sheet 5 N R F 1 v- I I I/VVEA/TOR GEORGES fizm'mua Arro/u/Er United States Patent 3,125,050 CONTROL SYSTEM FOR ELECTRIC SEWING MACHINES Georges Bertrand, 18 Rue de Toul, Paris, France Filed Mar. 6, 1961, Ser. No. 115,582 Claims priority, application France Mar. 11, 1960 6 Claims. (Ql. 112-419) My invention has for its object improvements in the control means for electric sewing machines of the type providing for a stoppage of the needle in at least one predetermined position.

It has already been proposed to use in sewing machines various arrangements for stopping the needle in at least one predetermined position.

One of these arrangements provides for a shaft connected with the needle and revolving in a continuous manner, disconnecting means and mechanical means including in particular an auxiliary motor adapted to provide in succession for the braking of the movable system connected with the needle and for its rotary shifting into a predetermined angular position corresponding to a selected position for the needle. Such an arrangement is intricate and costly.

Another arrangement which allows holding the needle against movement in a sewing machine resorts to two motors, the rotors of which are rigid with each other, while the stators, which are coaxial, are each connected in an independent circuit so as to provide for reversal of the direction of rotation of one of the motors during the setting of the needle in the desired position. The latter arrangement is also very intricate.

My invention covers a simple arrangement, which is easy to operate and which shows the advantage of obtaining selectively the holding fast of the needle in one of a plurality of predetermined positions, chiefly its upper dead point and its lower dead point, and slow operation of the needle, which can move stitch by stitch.

According to my invention, the electric motor control.- ling the sewing machine is of the series type and its normal running conditions correspond to a feed with alternating current under a voltage selected from the conventional voltages of the mains feeding the premises. Furthere, after interruption of these normal operative running conditions through disconnection of the supply of A.C., the motor is transformed into a shunt motor which is then fed with DC. under low voltage, reduced speed and high torque conditions. Switching oif means are provided in the DC. circuit so as to obtain selectively the feed with DC. voltage for a stitch by stitch operation of the needle, or else to break the DC. circuit at a predetermined moment corresponding to the stoppage of the needle in the desired position selected for it.

Said arrangement is more particularly applicable to a control system wherein the motor runs slowly and operates as a self-energized generator feeding the field windings. In such a case, the DC. supply operating under a low voltage is connected across the terminals of the field and armature windings, which are coupled in parallel so as to become actually operative only when the voltage of the generator drops underneath the voltage of the DC. supply, whereby the motor is driven in the direction of rotation originally assumed by it.

I will now describe my invention with further detail, reference being made to the accompanying drawings illustrating a preferred embodiment of the invention. In said drawings,

FIG. 1 is a wiring diagram of the arrangement driving the sewing machine, for normal operative conditions,

FIGS. 1a and 1b illustrate two of the three possible conditions of a selecting switch, its third condition being as shown in FIG. 1,

ice

FIG. 2 is a diagram similar to FIG. 1 with the changes provided for the braking of the motor to obtain the stoppage of the needle in a predetermined position or else for the progression of the needle stitch by stitch,

FIG. 3 is an axial sectional view of the rotary switch associated with the sewing machine,

FIG. 4 is a front view thereof as seen in the direction of the arrows IVIV of FIG. 3,

FIGS. 5 and 6 are views similar to FIGS. 3 and 4 of a modified embodiment of the rotary switch,

FIG. 7 is a diagrammatic view of the foot-controlled system provided on the sewing machine,

FIGS. 8 and 9 are views similar to FIG. 7 of two modifications of said system,

FIG. 10 is a front view of the switch controlling the motor,

FIG. 11 is a side view of said switch.

Turning to the embodiment illustrated in FIGS. 1 and 2, the electric feeding means include chiefly a primary switch 1 adapted to energize the motor and provided with four blades 2--34 and 5, of which the blade 4 is yielding while the others are rigid, and with three elastic blades 6-7 and 8 simultaneously movable through the agency of a common carrier member 9, whereby they may be shifted simultaneously in the direction of the arrow 1 in opposition to the action of a return spring (which is not illustrated); the elastic blades 6 and 7 engage the gap between the blades 2 and 3 while the elastic blade 8 engages the gap between the blades 3 and 4.

The stationary blade 2 is connected with a tapping 10 on the primary 11 of a transformer 12 of which one terminal 13 is connected with the stationary blade 5. The armature 14 of the motor driving the sewing machine is connected across the movable blades 7 and 8, while a rheostat 15 of the type constituted by a stack of carbon plates is connected across the movable blades 6 and 7. Field windings 17 are inserted across the stationary blades 3 and 5.

The blades 3 and 4 are connected across the terminals of a rectifying bridge 18 fed by one terminal of the secondary 19 of the transformer 12 in series with a rotary switch 20 froming the synchronizing switch and with a switch 21 forming the selecting switch.

The synchronizing switch 20 is provided with a conductive sector 22 connected permanently with the terminal of the secondary 19 opposed to that connected with the bridge 18 and with an insulated sector 23 of a smaller angular extent which is separated from the first sector 22 by insulating gaps 24 and 25.

Two diametrically opposed brushes 26 and 27 engage the periphery of the switch sectors 22 and 23 and are connected permanently with the corresponding blade 28 or 29 of the following selector switch 21 between which blades is inserted a blade 30 controlled by the operator and connected with the terminal of the rectifying bridge 1% opposed to that fed by the secondary 19.

The synchronizing switch 20 is driven synchronously with the shaft controlling the movement of the needle of the sewing machine through a transmission, of which several embodiments will be disclosed hereinafter.

For the medial position of the blade 30 incorporated with the switch 21, the blades 28 and 29 are bothv connected with the blade 30, as shown in FIG. 1. In contradistinetion when the blade 30 slopes towards the left hand side of FIG. 1, as shown separately in FIG. lb, only the blades 28 and 30 are still in contact and the blade 29 is disconnected; when the blade 30 enters a position sloping towards the right hand side, as shown separately in FIG. 1a, only the blades 29 and 30 are in contact while the blade 28 is disconnected.

The operation of the arrangement is as follows:

During normal operative running conditions (FIG. 1)

the blades 6, 7 and 8 of the primary switch are shifted in the direction of the arrow f so as to engage first the blade 2 with the blade 6 and the blade 3 with the blade 8. As soon as these contacts are established, the armature of the motor 14 is fed with the voltage appearing across the terminal 13 and tapping 10 of the transformer primary 11, in series with the field windings 17 and the rheostat 15. Said rheostat being of the type constituted by carbon plates, its resistance decreases with the increase in pres sure. At the beginning of operation, consequently, the motor is fed through a large resistance inserted in series and its speed is a reduced one. In order to increase its speed, it is sufficient to exert a larger pressure on the control member 9 in the direction of the arrow 1, which reduces the value of the adjusting resistance formed by the rheostat 15. After this shifting of the member 9, the rheostat 15 is short-circuited by the engagement obtained between the blade 7 and the blade 6.

During these successive operative stages, no rectified current is fed across the terminals of the rectifying bridge 18 since the blades 8 and 4 are insulated with reference to each other and cannot close the circuit for such a the pressure exerted in the direction of the arrow on the control member 9, so as to return the contact blades 68 into the position illustrated in FIG. 2; in other words,

'the blades 7 and 3 are then brought into contact with one another and the blades 8, 4 and are similarly brought into contact while the blade 2 is switched off the rheostat blade 6. Taking into account the presence of the DC. supply feeding through the blades 48, the motor is connected as a shunt motor whereas if this D.C. supply is not considered, the armature 14 is connected across the terminals of the field windings 17, and forms a selfenergized generator, the windings 17 and the rectifier 18 being inserted in parallel.

Thus, during the first stage of the closing of the contacts of the primary switch 1 as described, the armature 14 rotates at a high speed and forms a generator feeding current into the field windings 17, which leads to regenerative braking; the voltage produced across the 'terminals 3 and 4 is substantially higher than the voltage produced across the terminals of the rectifying bridge 18, so that last-mentioned voltage across the terminals is inoperative. The armature 14 is thus slowed down and as soon as its speed has become sufiiciently low, and the rectified DC. voltage becomes larger than the voltage across the terminals of the armature, the armature 14 and the field windings 17 are fed by the DC. voltage so that the motor operates as a shunt motor and continues rotating in the same direction as precedingly, but under low speed and high driving torque conditions. The rotary switch 20 is driven permanently in synchronism with the machine and the brushes 26 and 27 pass in succession over the insulated contact-piece 23.

If the blade 30 of the switch 21 is maintained in its medial position of FIG. 1, the motor is fed permanently .under low speed and high torque conditions with a DC. voltage and the machine operates stitch by stitch, as required for embroidery work for instance or for the accu rate stoppage of the seam when required, etc.

, ,If the blade 30 occupies, at the moment considered, the position shown in FIG. 1b, for instance, only the circuit passing through the brush 26 is capable of feeding direct current and, consequently the circuit feeding direct current is switch off each time the brush 26 lies on the insulated contact-piece 23, possibly after a few passages through a higher speed, as produced by reason of the inertia of the movable parts of the machine. This leads to periodical interruptions of the DC. circuit during the slowing down period of the motor. The needle stops then in the selected position, say in its uppermost position.

4 A similar operation is ensured when the blade 30 is brought into the right hand ,position shown in FIG. 1a, the needle being then stopped in its lowermost position for instance.

As defined hereinabove, the rotary switch 20 is driven synchronously with the main shaft of the machine, or

with any shaft rotating in synchronism with the movement of the needle.

FIGS. 3 and 4 show how movement may be tapped off for the synchronous switch through an elastic coupling arrangement including a suction cup 40 engaging under the action of a spring, which is not illustrated, the front surface of the hand wheel 41 of the sewing machine, said suction cup being carried at the end of the shaft 42 revolvably carried by a casing 43 with the interposition of roller bearings 44 and 45 While the brushes 26 and 27 are carried by the cup-shaped part 46 of the casing 43. The current is fed to the switch sector 22 for instance through the agency of two diametrically opposed brushes 47 and 48 lying at with reference to the brushes 26 and 27, said brushes 47 and 48 being both connected with a terminal of the secondary of the transformer 19. The operator may adjust in a simple manner the relative angular position of the shaft 42 and of the hand wheel 41 and consequently the position in which the needle is to stop.

According to a further embodiment (FIGS. 5 and 6), the rotary switch 20 is constituted by a disc 50 inside which is fitted an insulating sector 51, the remainder of the disc being conductive; the brush 48 which is connected with the secondary 19 of the transformer 12 is arranged substantially over the diameter of the disc while the brushes 26 and 27 lie along the path followed by the insulating sector 51.

The conductive disc 50 is secured to the end of a shaft 52 revolvably carried by roller bearings 53 inside a casing 54 held fast through a connection with the frame of the machine; the shaft 52 carries a ring 55 serving for reference purposes while the end of said shaft is secured adjustably by a locking pin 56 engaging a socket 57' rigid with the hand-wheel 58 of the sewing machine. The ring 55 carries a reference mark 55r, and the same is the case for the casing 54 which carries another reference mark 54r, said reference marks being selected in a manner such that when they are brought into registry, the switch 20 is in its current-breaking position, in other words one of the two brushes 26 or 27 engages the insulating sector 51. The adjustment of the switch is obtained simply by unscrewing the locking pin and by making the hand-wheel 58 of the sewing machine turn until the needle is brought into the position selected for its stoppage, generally a position which depends on the type of the machine and which corresponds substantially either to its upper dead point, or to its lower dead point. This being performed, the pin 56 is returned into its locking position.

In FIG. 7, I have illustrated diagrammatically a man ner of executing the control system referred to hereinabove. In said figure, the body of the sewing machine 60 secured to a table 61 is driven through the agency of a belt by a motor 63. A control casing 64 enclosing the primary switch v1 and the rheostat 15 is secured inside a drawer above the motor; the control or carrier member 9 is operable against the action of a return spring 71 by a chain 65 secured to the front end of a pedal 66 pivotally secured to a spindle '67. The engagement of the pedal by the tip of the operators foot produces a shifting of the member 9 in the direction of the arrow f, against the action of the return spring 71; in other words it leads to the starting of the motor fed under the AC. voltage of the mains with a progressive and gradual cutting out of the starting resistance formed by the rheostat 15.

The selector switch 21 is positioned in a casing 7-2 and a second chain 69 is secured to its. control lever 68 acting:

on the blade 30 (-FIG. 1), said chain being secured to the rear end of the pedal 66; a tensioned spring 70 urges the control member 68 upwardly.

For the inoperative posit-ion of the pedal 66, the 'blade 30 of the selector switch engages one of the blades 28 or 29 so as to provide for a stoppage of the needle in its uppermost position. Upon depression through the operators heel, the pedal 66 produces in succession a slow operation of the needle stitch by stitch and then a stoppage of the needle in its lowermost position.

It will be remarked that act-ion on one chain releases the other chain, and consequently the effects obtained by the two chains are not in conflect.

Upon releasing of the pedal which had been originally depressed by the operators heel, the needle rises immediately into its uppermost position.

In the further embodiment illustrated in FIG. 8, the elements are similar to those illustrated in FIGURE 7 with the addition of a spring 73 acting in opposition to the spring 7t) of the selecting switch and which is sufficient to return the lever 68 into its lowermost abutting position while the chain 69 is stretched and the chain 65 is very slack. Upon depression of the pedal 66 in the direction of the arrow f, the selecting switch 21 in the casing 72 is first operated, the needle passing from a first position of stoppage, through a position of stitch by stitch operation, into a second position of stoppage after which the primary switch 1 carried in the casing 64 and providing normal control is operated with the gradual cutting out of the starting resistance constituted by the rheostat 15.

In the embodiment illustrated in FIG. *9, the levers 9 and 68 are interconnected by a small bar 74- and a single chain 75 is secured between said bar 74 and the inner end of the pedal 66. The action of the spring '70 is less energetic than that of the spring 71 and consequently the depression of the pedal 66 acts first on the lever 68 until the cooperating end of the bar 74 engages the stop 76 after which the lever 9 controlling the primary switch 1 inside the casing 64 is shifted in its turn, since the bar 74 bears now against the lower stop 76. Sudden release of the pedal, even if it has for its result the simultaneous rising of the levers 9 and 68 under the action of the springs 71 and 70 into their upper positions, leads to no disturbance in operation, since only the shifting into its upper abutting position of the lever 68 can produce the connections which allow feeding the motor with low DC. voltage.

In FIGS. 10 and 11 is illustrated the casing 64 containing the primary switch 1 and the rheostat 15. It will be remarked that the movable blades 6, 7 and 3 are carried by a support 80- pivoting around a spindle 81 provided with a finger 82 operable through the fork-shaped end 835 of the lever 9, which pivots round an axis 84 and is subjected to the action of the chain 65, which action is exerted in opposition to the return spring 71. The latter spring urges the movable system into the position illustrated corresponding to self-braking and coupling of the motor as a shunt motor.

The resistance or rheostat 15 is of the type including a stack of carbon plates fitted inside an insulated tube provided with cooling fins. The value of said resistance 15 depends on the pressure exerted on the plates and the resistance includes a movable end-piece 85 subjected to the action of a small blade 86 rigid with the movable support 80 for the blades 6 and 8. The blade 6 is provided furthermore with an auxiliary blade 87 adapted to exert pressure on said end-piece 85 while the blade 6 engages the stationary blade 2.

The electric connection between the blades 2 and and the blades 6 and 8 respectively is the same as that illustrated in FIGS. 1 and 2.

The area through which the lever 9 is adapted to rotate is limited by a member 88 adapted to pivot round an axis 89 and including an adjustable stop 90 while the lever 9 is provided with an arcuate projection 91 having its center on said axis 89 so as to cooperate with the stop whatever may be the angular position of the support St). This arrangement allows adjusting the stroke allowed for the lever 9 and consequently limiting if required the rate of reducing the resistance formed by the rheostat 15 with a view to reducing the maximum speed conditions of the motor.

My invention obviously includes all the modifications falling within the scope of the accompanying claims and relating in particular to the control means and to the selecting switch. The latter may be carried either directly on the frame of the machine, or else it may be independent and be actuated manually.

The connection of the synchronizing switch may be ensured through a yielding cable enclosing three wires and connected with a connecting plug including three aligned male pins so that it is possible to modify with reference to the position of equilibrium of the pedal the control of the upper and lower positions of the needle through a mere pivotal movement of the plug through whereby each of said positions is obtained instead of the other during operation.

I may now mention the various advantages obtained through the above-described control system:

It ensures the electrical braking of the rotary system and then the slow operation under large torque conditions for the motor so as to provide a stoppage for the upper or lower position of the needle, or else it allows operation stitch by stitch,

It may be associated with the extant control system by providing a further contact blade in the switch 1 controlling the motor, a When associating the machine with a transformer, which is of interest for the feeding of the rectifying bridge, this allows feeding easily motors designed for different voltages so as to reduce the number of types to be resorted to and also it may allow the feeding of an illuminating bulb, such as the bulb L shown in FIGS. 1 and 2, under low voltage conditions which bulb is then less sensitive to vibrations than a lamp operating under the voltage of the mains. It will be remarked that the secondary of the transformer is equipped with tappings with a view to obtaining an optimum adjustment of the DO. feed voltage in accordance with the characteristic curves of the resistant torque and inertia of the machine.

As a supply of DC. I may also resort either to a simple battery or to any other rectifying means requiring a transformer or otherwise.

' The above-described control system may be simplified and reduced to only a number of components for instance when it is desired to obtain only the stoppage of the needle in a predetermined position without any stitch by stitch operation. In this latter case, it is possible to omit the selecting switch and it is also possible to reduce the size of the feed transformer when a direct connection is provided with the network feeding the motor without any possibility of selecting the voltage feeding the motor.

What I claim is:

l. in an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of AC, a supply circuit normally connecting said source and said windings in series, a rectifying bridge, a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch simultaneously disconnecting said source with reference to the windings and closing the second circuit to make the -motor run under low voltage, low speed, high torque conditions as a DC motor fed by the second circuit, and means moving synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

7 2. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rectifying bridge,

a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch simultaneously disconnecting said source with reference to the windings and closing the second circuit to make the motor needle, a motor controlling the reciprocation of the needle and including an armature winding and a field Winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rectifying bridge,

a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the Windings in parallel relationship, a primary switch simultaneously disconnecting said source with reference to the windings and closing the second circuit to make the motor run first as a self-energized braking generator rotating at a decreasing speed and then, after a predetermined lowering of the voltage produced by said generator, under low voltage, low speed, high torque conditions as a DC. motor fed by the second circuit, and means moving synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

4. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature Winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rectifying bridge, a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the .windings in parallel relationship, a primary switch simultaneously disconnecting said source with reference to the windings and closing the second circuit, a rotary switch moving in synchronism with the needle and including a ring constituted by two arcuate sections, the cooperating ends of which are separated by gaps, one and only one ring section at a time being connected within said first circuit, two auxiliary wires, stationary brushes connected with each of said wires and engaging diametrically opposed points of the switch ring, and operator-controlled switching means adapted to connect selectively one of or both the auxiliary wires within the first circuit to provide selectively continuous maintenance of the first circuit in its closed position and opening of said tfirst circuit at one of two moments corresponding to predetermined positions of the needle.

5. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rectifying bridge, a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch including two series of bladesadapted to occupy two positions with reference to each other, an operator-controlled member adapted to shift them from one position to the other, elastic means urging said blades into the position for which the said windings are in parallel relationship, the second circuit being eventually closed to make the motor run under low voltage, low speed, high torque conditions' as a D.C. motor, operation of the hand-operable member against the elastic means simultaneously disconnecting the output of the rectifying bridge and connecting the two windings in series across the supply of AC. and means moving synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

6. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rheostat normally inserted in series with the windings and including a stack of superposed carbon plates and a tin-carrying cover for said stack, a rectifying bridge, a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch including two series of blades adapted to occupy two positions with reference to each other, an operator-controlled member adapted to shift them from one position to the other, elastic means urging said blades into the position for which the said windings are in parallel relationship, the second circuit being eventually closed to make the motor run under low voltage, low speed, high torque conditions as a DC. motor, operation lOf the hand-operable member against the elastic means simultaneously disconnecting the output of the rectifying bridge and connecting the two windings in series across the supply of A.C., further blades controlled by said operator-controlled member when urged against the elastic rneans to compress to an increasing extent the rheostat to reduce its resistance, and means moving synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

7. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rectifying bridge, a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch including two series of blades adapted to occupy two positions with reference to each other, a pivoting support for said movable blades including an outer projection, a forked control lever pivotally shiftable between two angular positions in a plane orthogonal with reference to the pivotal axis of said support and adapted to act on said projection to make said support shift one series of blades between two predetermined relative positions with reference to the other series, elastic means urging said blades into the position for which the said windings are in parallel relationship, the second circuit being eventually closed to make the motor run under low voltage, low speed, high torque conditions as a DC. motor, operation of the hand-operable control lever against the elastic means simultaneously disconnecting the output of the rectifying bridge and connecting the two windings in series across the supply of A.C. and means moving synchronous ly with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

8. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rheostat normally inserted in series with the windings and including a stack of superposed carbon plates and a fincarrying cover for said stack, a rectifying bridge, a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch including two series of blades adapted to occupy two positions with reference to each other, a pivoting support for said movable blades including an outer projection, a forked control lever pivotally shiftable between two angular positions in a plane orthogonal with reference to the pivotal axis of said support and adapted to act on said projection. to make said support shift one series of blades between two predetermined relative positions with referenw to the other series, elastic means urging said blades into the position for which the said windings are in parallel relationship, the second circuit being eventually closed to make the motor run under low voltage, low speed, high torque conditions as a DC. motor, operation of the hand-operable control lever against the elastic means simultaneously disconnecting the output of the rectifying bridge and connecting the two windings in series across the supply of A.C., further blades controlled by said control lever when urged against the elastic means to compress to an increasing extent the rheostat to reduce its resistance, an adjustable stop limiting the movement of the control lever in the direction opposite to the action of the elastic means, and means moving synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

9. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rheostat normally inserted in series with the windings and including a stack of superposed carbon plates and a tin-carrying cover for said stack, a rectifying bridge, a first circuit connecting said source with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch including two series of blades adapted to occupy two positions with reference to each other, a pivoting support for said movable blades including an outer projection, a forked, operator-controlled lever pivotally shiftable between two angular positions in a plane orthogonal with reference to the pivotal axis of said support and adapted to act on said projection to make said support shift one series of blades between two predetermined relative positions with reference to the other series, said lever including an iarcuate section lying in a plane perpendicular to the pivotal axis of the support when the lever is in one position, elastic means urging said blades into the position for which the said windings are in parallel relationship, the second circuit being eventually closed to make the motor run under low voltage, low speed, high torque conditions as a DC. motor, operation of the hand-operable control lever against the elastic means simultaneously disconnecting the output of the rectifying bridge and connecting the two windings in series across the supply of A.C., further blades controlled by said operator-controlled lever when urged against the elastic means to compress to an increasing extent the rheostat to reduce its resistance, a stop limiting the movement of the lever in the direction opposite to the action of the elastic means, means for shifting said stop along an ancuate line matching the arcuate section of the lever, and means moving synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

'10. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally conmeeting said source and said windings in series, a supply of DC, a further circuit connecting said -D.C. supply with the windings in panallel relationship, a primary switch simultaneously disconnecting said A.C. source with reference to the windings and closing said further circuit to make the motor run under low voltage, low speed, high torque conditions as a DC. motor fed by said further circuit, and means moving synchronously with the needle and breaking said further circuit at a predetermined moment corresponding to a predetermined position of the needle.

11. In. an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a rectifying bridge, a transformer including a primary fed by said supply and a secondary, a first circuit conmeeting the transformer secondary with the input of the rectifying bridge, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relationship, a primary switch simultaneously disconnecting said source with reference to the windings and closing the second circuit to make the motor run under low voltage, low speed, high torque conditions as a DC. motor fed by the second circuit, and means mowing synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

12. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature winding and a field winding, a source of A.C., a transformer fed by said source and including a secondary and a primary, a supply circuit including said primary normally connecting said source and said windings in series, a rectifying bridge, a first circuit connecting said tuansformer secondary with the input of the rectifying bridge, an illuminating bulb fed by said transformer secondary, a second, normally open circuit connecting the output of the rectifying bridge with the windings in parallel relations-hip, a primary switch simultaneously disconnecting said source with reference to the windings and closing the second circuit to make the motor run. under low voltage, low speed, high torque conditions as a DC. motor fed by the second circuit, and means, moving synchronously with the needle and breaking the first circuit at a predetermined moment corresponding to a predetermined position of the needle.

13. In an electric sewing machine, the combination of a needle, a motor controlling the reciprocation of the needle and including an armature Winding and a field winding, a source of A.C., a supply circuit normally connecting said source and said windings in series, a supply of DC, a further circuit connecting said D.C. supply with the windings in parallel relationship, a handwheel for manual adjustment of the position of the needle and moving in synchronism with the latter, a primary switch simultaneously disconnecting said A.C. source, with reference to the windings, a member removably fitted on the handwheel in an angularly adjustable relationship with the latter, and means controlled by lastmentioned member and adapted to break said further circuit for a predetermined angular setting of the handwheel.

14. In a machine as claimed in claim 10; the provision of selecting means inserted in said further circult and adapted to provide selectively maintenance of the further circuit against breaking by the synchronous means [and execution of said breaking at one of two predetermined points of the cycle of operation of the needle, a control lever for said selecting means, a control lever for the primary switch, a pedal, a chain connecting the opposite ends of the pedal with the cor- 11 responding control levers, and springs urging the two control levers into a raised position.

15. In a machine as claimed in claim 110', the provision of selecting means inserted in said further circuit and adapted to provide selectively maintenance of the further circuit against breaking by the synchronous means and execution of said breaking at one of two predetermined points of the cycle of operation of the needle, a control lever for said selecting means, a control lever for the primary switch, a pedal, a chain connecting the opposite ends of the pedal with the oontnol levers, the chain corresponding to the primary switch being slacker than the other chain, springs urging the two control levers into a raised position, and a third spring acting on the pedal in opposition to the spring acting on the control lever for the selecting means.

'16. In a machine as claimed in claim 10, the provision of selecting means inserted in said further circuit and adapted to provide selectively maintenance of the further circuit against breaking by the synchronous means and execution of said breaking at one of two predetermined points of the cycle of operation of the needle, a contnol lever for said selecting means, a control lever for the primary switch, a pedal, a link pivotally interconnecting the two control levers, a stop adapted to be engaged by said link for the lowermost position of the control lever for the selecting means, a chain interconnecting the link with the pedal, at a point such that the depression of the bar by the pedal through the chain shifts the control lever for the selecting means before the other control lever.

References Cited in the file of this patent UNITED STATES PATENTS 1,483,441 Hibbard Feb. 12, 1924 1,517,290 Hibbard Dec. 2, 1924 2,536,012 Turner Dec. 26, 1950 2,961,591 Frankel et al. Now. 22, 19-60 

1. IN AN ELECTRIC SEWING MACHINE, THE COMBINATION OF A NEEDLE, A MOTOR CONTROLLING THE RECIPROCATION OF THE NEEDLE AND INCLUDING AN ARMATURE WINDING AND A FIELD WINDING, A SOURCE OF A.C., A SUPPLY CIRCUIT NORMALLY CONNECTING SAID SOURCE AND SAID WINDINGS IN SERIES, A RECTIFYING BRIDGE, A FIRST CIRCUIT CONNECTING SAID SOURCE WITH THE INPUT OF THE RECTIFYING BRIDGE, A SECOND, NORMALLY OPEN CIRCUIT CONNECTING THE OUTPUT OF THE RECTIFYING BRIDGE WITH THE WINDINGS IN PARALLEL RELATIONSHIP, A PRIMARY SWITCH SIMULTANEOUSLY DISCONNECTING SAID SOURCE WITH REFERENCE TO THE WINDINGS AND CLOSING THE SECOND CIRCUIT TO MAKE THE MOTOR RUN UNDER LOW VOLTAGE, LOW SPEED, HIGH TORQUE CONDITIONS AS A D.C. MOTOR FED BY THE SECOND CIRCUIT, AND MEANS MOVING SYNCHRONOUSLY WITH THE NEEDLE AND BREAKING THE FIRST CIRCUIT AT A PREDETERMINED MOMENT CORRESPONDING TO A PREDETERMINED POSITION OF THE NEEDLE. 